Modern Vespa

Ok guys

I've had my VBB for a couple weeks now and I haven't done much besides ride it around the neighborhood and replace bulbs and small chrome bits.

The engine has been leaking since I got it. It runs like a champ but it is dripping a decent amount on the garage floor now. I plan on tearing the entire bike apart in the near future but for now I wan't to make sure the leaks won't do any permanent damage. I'm want to learn so help me out.

I took some pics of the oil leaks. It is actually pooloing up on the floorboards a bit too which is weird because its hard to tell how it got all the way up there. My guess its running underneath the body and coming up but when looking underneath it doesn't seem to be the case?

It also looks like there may be a rubber plug missing in figure #2 and a leaking plug in figure #1. This is on the back of the case under the airbox.

Explain this to me please.

is it 2 stroke oil/gas or gear oil?

Not sure what #2 is, but #1 is the mixture screw plug.

Is it leaking from the mixture screw plug? Try using a degreaser and clean up the oil spill around that area, pop the mixture screw plug out w/ a flat head screw driver, then do a quick ride. If it's leaking from there, then you should see an oil trail from there or you can just open the air box to see if there's a puddle there.

Try replacing the carb base gasket, use degreaser to clean up the oil, and ride again to see if it's leaking.

see instructions from removing airbox to replacing carb base gasket.
http://vespamaintenance.com/engine/teardown/index.html

It seems figure #1 is the highest point where I see a leak on the motor. You can even kinda see this if you look closely in the 2nd pic. The color appears to have a slightly redish tint to it.

does it smell like gas?

you should clean off all the exposed area and find out where the leak is coming from before you do any disassembly. once you start pulling apart the engine you lose the chance to do the job right, the first time.

oh and some leakage from #1 is normal. the rotary pad area spits up some gas through the filter and out this hole.

If it has a rubber plug over that hole, I don't see how it is getting out and in quantity?

have you tipped it over and /or taken off the back wheel yet


most likely thats where all the mix is coming from you'll see if you look at the back of the carby,,,,,,,,why

no

oh well ....... do it so you'll see if you can be bothered






mine looks grottier than that,and i just cleaned it



the fuel evaporates leaving you with oily shit that drips off wherever


could be something else but take off the back wheel and look there first

at least that should be simple , for simple things first



good luck

There are some earlier posts about warped carbs and how you would have to use sand paper to level the base. Though, I would first check if there is oil in the carb box and replace the carb base gasket.

Clean,tighten carb/ air box.
These 2strokes spit a little mix out the filter it's just the way it is.

If it is leaking out of the carb box near the mixture screw grommet, you need to clean and adjust your carb, paying attention to the float and needle. Even if I'm wrong, it's still a good idea.

For reference, #2 is a spot in these engines where an INTERNAL HT coil would have run the spark plug wire through.

Older engines, particularly VNB's, have a stator with an HT coil built onto it... and a spark plug wire coming off of it and running right to the spark plug....exiting through this hole.

It would appear someone has converted your onboard HT-coil stator to a normal external HT coil one. ( which i approve of, as it makes troubleshooting easier. )

All it does is go to the stator area, though ... so there should be NO oil coming out of it... perhaps just leaking into it as it drips down from your carb box.

Oil on the floorboards means you likely have a leaky gas tank, which is dripping down into the frame and seeping between the floorboard welds.

I'd address your leaky tank problem first ( possibly by either ensuring a clamp on the fuel hose, or replacing the fuel tap packing ). Then i'd figure out why your carb is burping so much. Could be too large a main jet, allowing more gas to belch back up. All vespas do this to a small extent. My SS and GS have a little hose from the carb box down the back of the engine to the ground, so that this extra gas is vented off away from the engine cases.

Thanks Eric...... I will begin my search for the leak. Shoould I put a fubber grommet in figure #2 to avoid getting any more crap in there?

I'm gonna suggest an alternate cause, that's backed up by leakage out of the mixture screw hole. I think you are pooling a lot of gas inside of your air box--not from it spitting up while the bike is running, but from something leaking. If you get enough gas in the airbox, it can run through the air bellows and into the frame and seep out of the floorboard. Trust me, I've seen it happen.

Check the fuel banjo and the float bowl lid for tightness, and like others have said, make sure your carb bolts are tight enough and check the carb base gasket and airbox-to-case gasket.